On Wednesday the 18th, SpaceX advanced testing of "the odd one out" of the fleet of Starships, Ship 26. It has been on a test stand not far from the launch pad and going through various proof tests, things like cryogenic fuel loading and, pressure testing and all, culminating Wednesday in a test that ignited one engine for a short test.
In case you haven't been watching this ship in development, you can see Ship 26 isn't like the others we've seen. No thermal tiles, no "flings" - those combination aero flaps and wings that are used to steer the ship after its hypervelocity atmospheric reentry aren't needed because no thermal tiles means 26 will never reenter. If it ever goes into orbit, it will be destroyed on the way down.
While I've never seen anything officially stating this, I've believed from the start that 26 is going to be the ship that goes to orbit to work on developing on-orbit refueling, and if it's not 26, it's going to look like her in not having thermal tiles and aero surfaces.
Ship 26 rolled to the test area in Boca Chica for testing on September 7th, so she has been there for over a month. Today, they advanced to a full duration static fire. (a 1min 34 second video with several views of the test).
The only thing about this that's a bit strange is that it appears to be only one engine, judging by watching it a 1/4 speed - and the screen capture still-photo that NASASpaceflight uses above. Which raises the question of whether or not ship 26 is supposed to have more than one engine. It just has to make orbit and then make occasional small moves. It won't reenter so it doesn't need the sea level raptors. If another Starship gets to 26 on orbit and transfers all its fuel, does it need more than one vacuum Raptor engine to reach orbit? The normal set of three?